Genome sequencing is expanding our knowledge of the sequence of cellular proteins, DNA, and RNA at a pace that surpasses our understanding of their function. Sequence data alone cannot elucidate the role of a protein in cellular processes and pathways, but can be used to design an oligonucleotide-based antisense or antigene approach as a simple route to "knock out" phenotypes. Many laboratories have tried this, but their success has been limited because it has been difficult to predictably design oligonucleotides that function in a potent and selective manner. Peptide nucleic acids (PNAs) are oligonucleotide mimics that possess a nonionic amide backbone. They have been demonstrated to possess substantial advantages for hybridization in cell free systems, and the goal of this proposal is to determine whether they possess similar advantages for hybridization within cells. The investigators specific aims are to (i) optimize delivery of PNAs into cells, (ii) use PNAs to control gene expression by targeting mRNA, and (iii) use PNAs to control gene expression by targeting genomic DNA. Their research is relevant to human health because the substantial advantages that PNAs possess for hybridization to complementary targets suggest that they will be useful tools for translating genome data into knowledge of the details of protein function within cells. In addition, PNAs may provide a new generation of antisense agents that improve on first generation therapeutics that have already shown promise in clinical trials. Information generated by this proposal will facilitate evaluation of PNAs as a strategy for targeting human disease and provide a powerful approach for translating the one dimensional understanding of protein function derived from genomic data into the multidimensional understanding necessary to understand cell signaling and regulation.